EE WAS USING A SCOOP TO CLEAR GOB, A PIECE OF RIB, STONE/COAL MIX FELL OUT STRIKING CANOPY. A PIECE CAME IN CAB STRIKING VICTIM ON BACK. CAUSE OF INJURY WAS AWARENESS & KNOWLEDGE. COMPLIANCE W ITH RULES/REGS NOT A FACTOR, MINE EQUIP/SYSTEMS NOT A FACTOR, JOB SKILLS AND MINER PROFICIENCY MAY BE A FACTOR. PROTECTIVE DEVICES ON EQUIPMENT A FACTOR.